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Relationships Between Saturation Deficit and The Survival and Distribution of Terrestrial Isopods
- White, Joseph J., Zar, Jerrold H.
- Ecology 1968 v.49 no.3 pp. 556-559
- Isopoda, equations, habitats, longevity, relative humidity, specific gravity
- Equations are presented (1) to determine the specific gravity of a glycerol—water solution necessary to maintain a desired relative humidity in a small experimental chamber and (2) to predict the relative humidity which would be maintained by a given glycerol—water solution. The woodlouse, Tracheoniscus rathkei Brandt can survive its normal life span only if exposed to saturation deficits very near zero. In this species, as well as in 8 previously reported species, survival time is inversely related to saturation deficit rather than simply to the relative humidity. When equations for this relationship are compared for the various species, it is observed that those species whose survival times are decreased most by increases in saturation deficit are those which are normally found in wetter habitats.